Before a workpiece is combined with other workpieces to form an assembly, it is typically machined to a desired shape and dimension. Often, such a machining process is performed by a cutting tool, which modifies the component by removing material from a surface of the workpiece. This material removing process is achieved by moving a cutting edge of the tool along a surface of the workpiece at a particular velocity and depth. As the cutting edge moves along the surface, workpiece material is sheared along a shear plane to form a chip. Frictional forces resulting from the movement of the cutting edge across the surface of the workpiece can generate a significant amount of heat, which may contribute to wear on the cutting tool and/or may damage the workpiece.
One attempt to reduce the amount of heat generated by the frictional forces is disclosed in U.S. Publication No. US2006/0123801 (the publication), by Jackson on Jun. 15, 2006. The publication describes a cutting tool having axially bored channels running the length of the tool and terminating prior to a cutting edge. In addition, each channel includes a free floating capillary tube. A coolant such as solidified carbon dioxide (CO2) particles is directed through each capillary tube while a propellant such as CO2 gas is directed between the inner walls of the channel and the outer walls of the capillary tube. Either at or prior to the interface between the cutting tool and the workpiece, the coolant and propellant are mixed together to form a cryogenic spray that cools and lubricates the interface between the cutting tool and the workpiece.
Although the cryogenic spray disclosed in the publication may lubricate and cool the interaction between the cutting tool and the workpiece, its effectiveness may be limited. In particular, the configuration of the cutting tool requires directing two different fluid streams through the tool and mixing the streams prior to the interface between the cutting tool and the workpiece without any feedback that may be used to adjust the mixture. Such a configuration increases the complexity of the system because it may be difficult to maintain a consistent mixture composition without any feedback. For example, the percentage of the mixture that includes the coolant may vary throughout the cutting process. Such a variance in the composition of the mixture can make the lubricating and cooling properties of the mixture unpredictable.
Additionally, the efficiency of the cryogenic spray disclosed in the publication may be reduced because the cryogenic spray is directed through the shank of the cutting tool and not through the cutting insert. In this configuration, the coolant delivery point is located away from the interface between the tool and the workpiece. While traveling through the space between the delivery point and the interface, the temperature of the cryogenic spray may increase before reaching the interface. Furthermore, currents in the ambient air surrounding the tool and workpiece may direct some of the cryogenic spray away from the interface. Therefore, more cryogenic fluid may be needed to obtain a desired lubrication and temptation.
The disclosed system is directed to overcoming one or more of the problems set forth above.